1. Field of the Invention
The present invention relates to an apparatus for the smoothing of a material web, e.g., a paper or card web. The apparatus include at least one smoothing zone through which the material web is passed.
2. Discussion of Background Information
A calender of the type generally described above is disclosed, e.g., in EP 0 361 402 A1. In this calender, the smoothing zones are respectively formed between a heated chill-cast roll and an endless band formed with a soft or resilient cover. A smoothing process of this type always occurs at a side of a material web that contacts the respective chill-cast roll. Accordingly, a relatively heavy, heated, chill-cast roll, which requires long heat up and cool down times, must be used. Moreover, the chill-cast roll is only capable of being handled with heavy apparatus.
This known calender is relatively expensive and complicated in its construction. Further, when it becomes necessary to exchange these heavy rolls, and subsequently necessary to heat the new rolls, considerable cost arises in this complex exchange. The use of a heated, chill-cast roll with corresponding bearings involves a series of disadvantages which relate, e.g., to its large mass, the long heating up and cooling down times and to the fact that corresponding handling is only possible with heavy apparatus. Thus, it is apparent that the use of rolls is extremely costly. Moreover, at least one complete replacement roll must be kept available. Further, zonal heating is not practicable due to the considerable cost which is associated with the requisite induction segments.
Finally, correspondingly high pressures and high temperatures are necessary for large rolls.